1. Field of the Invention
The present invention relates to a projection apparatus, and more particularly to a projection apparatus with a better cooling effect.
2. Description of Related Art
Please refer to FIG. 1. FIG. 1 is a schematic view showing a conventional apparatus structure. A conventional projection apparatus 100 comprises a housing 110 and a light source 120, imaging system 130, optical engine 140, power supply 150, blower 160 and axial fan 170 installed in the housing 110. The housing 110 is provided with a top plate (upper portion of the housing 110) (not shown in the figure), bottom plate 111 (bottom portion of the housing 110) and a plurality of side walls 112a, 112b, 112c and 112d connected with the top plate and the bottom plate 111. An air outlet 180 is disposed on a corner formed between the side walls 112a and 112b and the light source 120 is installed adjacent to the air outlet 180. The imagining system 130 including, for example, the lens and/or mirrors is installed at a corner between the side wall 112c and the side wall 112a. The optical engine 140 including, for example, lens, rod or light harmonization device, is installed between the imagining system 130 and the light source 120. The power supply 150 is installed at a corner between the side wall 112c and the side wall 112d. Besides, the blower 160 is installed adjacent to the optical engine 140 between the side wall 112d and the light source 120. Furthermore, an air inlet 190 is disposed on the side wall 112c. 
The blower 160 has an exhaust port 162 and a suction port 164, in which the exhaust port 162 faces the light source 120 and the side wall 112b, and the suction port 164 faces the optical engine 140 and the side wall 112a. The axial fan 170 has an exhaust port 172 and a suction port 174, in which the exhaust port 172 faces the light source 120 and the side wall 112a, and the suction port 174 faces the side wall 112d. 
The light source 120 is driven to illuminate by electricity provide through the power supply 150 in the projection apparatus 100. A light beam emitted from the light source 120 is passed through the optical engine 140 and the imagining system 130 to display an image onto a screen (not shown). The blower 160 and the axial fan 170 are needed to cool the light source 120 since the light source 120 generates a lot of heat when the projection apparatus 100 is operated. In the conventional technology, air outside the housing flows into the projection apparatus 100 through the air inlet 190, the air passed through the power supply 150 to take away the heat from the power supply 150 to decrease the temperature in the power supply 150. Next, the axial fan 170 inhales the air from the power supply 150 via the suction port 174 and expelling the air through the exhaust port 172. The air expelled out from the axial fan 172 passes through the light source 120 and flows out of the projection apparatus 100 through the air outlet 180 such that part of the heat generated from the light source 120 is dissipated out of the projection apparatus 100. The suction port 164 of the blower 160 inhales the air passed through the imaging system 130 and the optical engine 140 and then expels the air via the exhaust port 162. The air expelled from the blower 160 passes through the light source 120 and flow out of the projection apparatus 100 via the air outlet 180 to take away part of the heat from the light source 120 out of the projection apparatus 100.
Accompanying the performance enhancement of the projection apparatus 100, the energy consumption is also increased. For example, for displaying a high brightness images, the power of the light source is increased to elevate the illumination brightness, but the heat generated from the light source 120 and the power supply 150 is also caused to increase so that the original cooling mechanisms cannot decrease the temperature inside the projection apparatus 100 effectively. Therefore, the original speed of the axial fan 170 running higher or replacing a larger axial fan may be required to elevate the cooling efficiency. However, the high speed of axial fan results in a serious noise problem and the larger axial fan increases the dimension of the projection apparatus 100.
Please refer to FIG. 2. FIG. 2 is a schematic view showing another conventional projection apparatus structure. The difference between a projection apparatus 100′ and the projection apparatus 100 is that another air outlet 182 is disposed on the side wall 112d of the projection apparatus 100′ and an axial fan 175 is installed adjacent to the air outlet 182. The axial fan 175 increases the air flow inside the projection apparatus to dissipate the heat from the power supply 150 not the heat from the light source. In this way, the temperature of the projection apparatus 100′ is still high.